Having explored the basin, he was on his way to Oregon, when he learned that the Mexicans were plotting to kill all the Americans in the valley of the Sacramento River. He therefore turned back to northern California, and with a force made up in part of American settlers gathered from the country round about, he took possession of that region, marched as fast as possible to Monterey, and captured that place also. Within about two months he had conquered practically all of California for the United States. Fremont then made his home in California. On the 4th of the following July he was elected governor of the territory by the settlers then living there. Eleven years later the Republican party of the United States nominated him for President, but failed to elect him. He died in 1890. He has well been called "the Pathfinder." Fremont's conquest of California was, in effect, a part of the Mexican War, which began in 1846. After nearly two years of fighting a treaty of peace was signed, by which Mexico ceded to the United States not only California but also much of the vast region now included in Nevada, Utah, Arizona, and New Mexico. This region, which is called the Mexican Cession, contained five hundred and forty-five thousand seven hundred and eighty-three square miles, while Texas included five hundred and seventy-six thousand one hundred and thirty-three square miles. These two areas together were, like Louisiana, much larger than the whole of the United States at the end of the Revolution. With the addition of Louisiana in 1803, of Florida in 1819, of Texas in 1845, and of this region in 1848, the United States had enormously increased her territory. THE DISCOVERY OF GOLD On the same day on which the treaty of peace was signed with Mexico (February 2, 1848), gold was discovered in California. Captain Sutter, a Swiss pioneer living near the site of the present city of Sacramento--at Sutter's Fort, where Fremont stopped on his second expedition--was having a water-power sawmill built up the river at some distance from his home. One day one of the workmen, while walking along the mill-race, discovered some bright yellow particles, the largest of which were about the size of grains of wheat. On testing them, Captain Sutter found that they were gold. [Illustration: Sutter's Mill.] He tried to keep the discovery a secret, but it was impossible to prevent the news from spreading. "_Gold! Gold! Gold!_" seemed to ring through the air. From all the neighboring country men started in a mad rush for the gold-fields. Houses were left half built, fields half ploughed. "To the diggings!" was the watchword. From the mountains to the coast, from San Francisco to Los Angeles, settlements were abandoned. Even vessels that came into the harbor of San Francisco were deserted by their crews, sailors and captains alike being wild in their desire to dig for gold.